After three weeks of prosecution evidence against the doctor charged in the death of Michael Jackson, a court has heard witnesses describe him as a thorough and caring physician.

Several patients testified that Dr Conrad Murray offered his services free to the poor.

Dr Murray's eyes filled with tears as elderly patient Ruby Mosley recalled him founding a clinic in a poor community in Texas in honour of his father.

"If this man was greedy, he never would have come to an area where 75 per cent of the people are poor, on welfare and social security and where he was making less than where he was in Vegas," she said.

The 82-year-old witness told the court that the physician never turned away a patient even if they didn't have insurance or couldn't afford treatment.

Ms Mosley was the last of five character witnesses that Dr Murray's lawyers called during his trial for involuntary manslaughter in Los Angeles.